Increased intestinal clearance of α₁-antitrypsin in patients with α₁-antitrypsin deficiency

To evaluate the possible contribution of enteric losses ofα₁-antitrypsin (α₁-AT) to the low serum levels of a,-AT seen in patients with a,-AT deficiency, we investigated intestinal clearance of α₁-AT (C-α₁,-AT) in five of these patients (mean age 3.4 years) and compared it to that of 10 patients (mean age 3.7 years) with gastrointestinal disorders and normal serum albumin values who served as controls. C-α₁-AT was also determined in four patients (mean age 9 months) with noncirrhotic liver disease. The percent of daily α₁-AT turnover which could be attributed to stool losses was calculated in these groups of patients, α₁-AT was measured in stool and serum by radial immunodiffusion and the clearance calculated. The mean C-α₁-AT in the patients with α₁-AT deficiency was significantly (p < 0.05) higher than that of the controls. The liver disease patients had values for C-α₁-AT in the range of the controls. Three of the α₁-AT deficiency patients had values for C-α₁-AT greater than the mean plus 3 SD of the control, but these were not in the range seen in patients with protein losing enteropathy. Mean percent contribution of stool losses to total daily α₁-AT turnover was similar in all three groups. We conclude that patients with α₁-AT deficiency have increased fecal clearance of α₁-AT seemingly unrelated to the liver disease, but that this is not a major cause of the low serum levels.